May 22, 2008 -- In contrast to a previous study, results of a new critical evaluation indicate that sediment effect concentrations (SECs) are questionable "consensus" values. The researchers of the new study conclude that the SECs for polychlorinated biphenyls (PCBs) should be used only in the screening-level evaluations that typically precede more direct assessments of sediment toxicity at individual study sites. The study is published in the latest issue of Integrated Environmental Assessment and Management.
In 2000, a set of SECs was published for evaluating the toxicity of PCBs in freshwater, estuarine, and marine sediments. According to the developers, these consensus-based SECs reconcile existing sediment quality guidelines (SQGs) that have been developed using various approaches, reflect causal rather than correlative effects, and can be used to determine the spatial extent of injury to sediment-dwelling organisms.
In the present study, a critical evaluation of those consensus-based SECs was based on the original documents and databases used to develop the underlying SQGs as well as the original documents and data sets used to determine the predictive ability of the SECs. Results indicated that the SECs were simple mathematical constructs that share the same limitations as their underlying SQGs. The SECs were questionable "consensus" values because many of their underlying SQGs were dissimilar, misclassified, or redundant with other SQGs.
On the basis of this critical evaluation, researchers D. Scott Becker and Thomas Ginn concluded that the SECs for PCBs should be used only in the screening-level evaluations that typically precede more direct assessments of sediment toxicity at individual study sites, and should not be used to predict sediment toxicity. Contrary to the conclusions of the SEC developers, Becker and Ginn found that the SECs do not reconcile existing SQGs, do not reflect causal effects, and should not be used to determine the spatial extent of injury to sediment-dwelling organisms.
To read the entire study, Critical Evaluation of the Sediment Effect Concentrations for Polychlorinated Biphenyls (D Scott Becker and Thomas C Ginn), click here: http://www.allenpress.com/pdf/i1551-3793-4-2-156.pdf
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